1. Field of the Invention
This invention relates to a water-based magenta ink composition suited for ink-jet recording, and an ink-jet recording process making use of it.
2. Description of the Related Art
Ink-jet recording is a system in which ink droplets are formed by ink ejection methods of various types (e.g., a system utilizing electrostatic attraction, a system in which mechanical vibration or displacement is imparted to ink by the use of a piezoelectric device, and a system in which ink is heated to cause it to bubble and a pressure produced when it bubbles is utilized), and part or the whole of them is caused to adhere to recording mediums such as paper to make a record.
As ink compositions used in such ink-jet recording systems, those prepared by dissolving or dispersing water-soluble dyes or pigments of various types in water or mixed solvents of water and water-soluble organic solvents are known and put into use. Such ink compositions are required to have various performances most suited for what they are used. For example, they are required to cause no precipitation or aggregation even when unused for a long period of time, to cause no clogging at nozzles and in ink channels of the head of an ink-jet printer and to ensure good print quality. In particular, the performances most required are i) the recording performance or liquid stability that the ink composition does not cause clogging of, and deposits at, nozzles and ink channels of the inkjet printer head when recording is performed using the ink composition, when the recording is paused and also when the recording is stopped over a long period of time, ii) the quick-drying performance that recorded images quickly dry and do not blur even when touched with fingers, iii) the print quality performance that recorded characters, ruled lines and so forth are free from whiskery blurs (i.e., feathering), free from mutual color mixture of different colors at their boundary areas (i.e., bleeding) and formed as sharp images, and iv) the less smelling properties that ink itself less smells.
In comparison between dyes and pigments, the pigments are dispersed in ink mediums without dissolving, whereas the dyes completely dissolve in ink mediums. Hence, dye ink compositions may cause clogging at nozzles and in ink channels of the head of the ink jet printer with difficulty and have much superior liquid stability, compared with pigment ink compositions. Accordingly, many inks for ink-jet printers are dye ink compositions. As such dye ink compositions, water-based dye ink compositions formed of water and dyes dissolved therein are prevalent, and those in which water-soluble dyes having various chemical structures are dissolved in water or mixed solvents of water and water-soluble organic solvents and various additives are optionally added are chiefly used at present.
However, even for such water-based dye ink compositions having been made commercially available, it is difficult to satisfy all the liquid stability, quick-drying performance, print quality performance, stability and less smelling properties. Various improvements are studied but not yet satisfactory. Also, the sharpness and color tone of recorded images may change depending on the type of dyes used. With regard to ink compositions making use of acid dyes capable of giving especially sharp images, they have a poor water resistance. Moreover, among the acid dyes, Color Index Number Acid Red 52 can form magenta color with a sharp and good color tone, and on the other hand especially have a poor water resistance, having a great problem.